1. Field of the Invention
The present invention relates to data processing systems and more particularly to operating systems which can be tailored to meet installation-specific requirements.
2. Prior Art
Before productive work can be done on a data processing system (installation), the operating system must be initialized to specific starting values and states. The initialization of the operating system requires definitions and actions provided by generated values that are obtained from system generation, i.e. during the `SYSGEN` process, from the system parameter libraries, and from directives provided by the system operator. The initialization process tailors an operating system to meet specific user needs.
The operating system is actually a set of many components, each of which performs an initialization before it can enter the normal processing mode. Some operating system components are initialized during the initial program load by the stand-alone initial program loader (IPL) while others are initialized following IPL. Some components, although integral to the operating system, are initialized, enter normal processing, and are terminated as often as necessary and as directed by system operators. One such component is the job entry subsystem (JES) component of the operating system, e.g. of the IBM MVS or the IBM MVS/XA operating system. Generally, the JES program reads jobs into the data processing system, converts them to internal form, selects them for execution, processes their output and purges them from the system. JES is the job flow manager within the operating system.